VOF convergence

I'm solving a film flow over a plane with VOF. I'm having time steps of 10^-9, with underrelaxation factors of about 0.05, with PISO pressure-velocity coupling and Bodyweight pressure. The grid is quite coarse. Is there any trick to enhance convergence?

Right now I am post processing a film modeling. Whats your film thinkness. Pls tell me the detail film liquid properties, physical set-up, model you are using, what type of VOF (geo?, implicit steady?)..

Hi, thanks for your answer, here is the info; I'm modeling a film over a sphere of 1 mm, subject to gravity, the liquid has density of 780 kg/m3, 0.0024 kg/ms. I'm using VOF in axisymetrical coordinates with geo reconstruction and unsteady implicit formulation.

I've figured out that the initial setup of the simulation has a great influence in the convergence history, now I'm getting 10-7 sec of time step that ( I think is still too small).